a) Field of the Invention
The present invention relates to aircraft landing gear, and more particularly to such a landing gear which is particularly adapted to be used with larger aircraft and provide proper ground clearance and also clearance for inspection and maintenance of the landing gear.
b) Background Art
Airplanes commonly have retractable landing gear, where the landing gear has a stowed position within the airplane structure, and an operating position where the landing gear extends from the airplane structure so that the landing gear wheels can properly engage the ground surface. Accordingly, the fuselage of the airplane (or other body carrying the landing gear) is provided with landing gear well doors which remain closed during flight, but are opened before landing to permit the landing gear to be moved to its operating position for ground engagement upon landing of the airplane.
Proper utilization of space is, of course, very important for most all aircraft. Also, it is necessary to provide the various components of the airplane with proper access and clearance for maintenance, repair, etc. With landing gear, for example, it is desirable that when the airplane is on the ground, the landing gear doors and other components are positioned to provide proper clearance to facilitate wheel inspection and maintenance. Also there are minimum clearance requirements on both sides of the body to accommodate wheel change and supporting equipment.
A search of the patent literature has disclosed a number of devices related generally to aircraft or other transportation vehicles, showing various doors and other closure mechanisms for a variety of purposes. These are the following:
U.S. Pat. No. 2,378,856 (Laddon et al.) illustrates a xe2x80x9csliding closure for aircraftxe2x80x9d. In FIG. 1, there are shown the closure doors 24 which are flexible and move in tracks from a lower position (on the left side of FIG. 1) to an upper position (right side of FIG. 1). This could be used, for example, for providing a bottom opening for the discharge of bombs. FIG. 4 shows another embodiment where this could be used as a sliding enclosure for a tail gun compartment or xe2x80x9cany other access openingxe2x80x9d.
U.S. Pat. No. 2,445,131 shows a door mounting system for an aircraft where the door moves a short distance laterally in the channels 13-16. When the door is moved to the position in FIG. 3, the several rollers 26 become aligned with an upper channel 35 and the lower channel 36 and then the doors slip laterally to the position of the FIG. 5 to its open position.
U.S. Pat. No. 2,604,281 (McCall et al.) discloses a door structure for a bomb bays in the military aircraft. In FIG. 3, there is shown a linkage by which the two bomb bay doors 7 are moved outwardly to the open position. As can be seen in FIG. 3, the left door 7 pivots about the location 53, and is interconnected to the location 53 by a strut 65. A rod 69 is actuated by the hydraulic actuator 50 to move the arm 66 downwardly to in turn cause the strut 67 to push the door 7 upwardly and outwardly, rotating about the pivot point 73. The right door 70 is connected to an arm 55, the lower end of which connects to the right door 7 and the upper end of which connects at 77 to an actuating linkage connected to the hydraulic actuator 50. When the hydraulic actuator 50 is extended, this moves the upper end of the arm 55 on an arcuate path counterclockwise to open the right door 7.
U.S. Pat. No. 2,658792 (Scott) illustrates a door which is slid from a closed position parallel to the outside contour of the body to a forward position so that it is within the body of the vehicle.
U.S. Pat. No. 2,670,156 (Clark et al.) shows a catapult hook mechanism and FIG. 9 shows the door and the hinge mechanism by which the door 81 is moved. There are two L-shaped strips 86 and 87 pivotally connected at a center location, one being pivotally connected at 90 structure, and the other end at 95 to the door panel. The second member is mounted at 94 at a slot and has a pivot connection 92.
U.S. Pat. No. 2,921,501 (Parot) relates to a system for an aircraft to release a load, such as bombs. FIG. 5 shows a mechanism for opening the two lower doors 2. There is provided a pair of arms which are actuated by the member 7. Each of the doors has two rollers which fit in respective curved tracks 29 and 30 to move the doors out of their closed position, then rotate these upwardly to the position within the fuselage, such as shown in the broken lines at the left of part of FIG. 5.
U.S. Pat. No. 3,174,712 discloses a hold door for an aircraft. This is designed so that the door can have a circular cross sectional configuration to conform to the contour of the fuselage. The door member 6 and 7 are mounted in sideways so that these can move from the closed position in a circular path upwardly along the outside of the fuselage.
U.S. Pat. No. 2,486,721 (Miczinski) shows a closure flap assembly for a lift drive mechanism in an aircraft. There are two flaps 1 and 6. The forward flap is pivotally located at a forward location and is rotated about that pivot location by a link 4 which rotates counterclockwise (see FIGS. 1-3) to move the door from the closed position (FIG. 1) to the open position (FIG. 3). The swing end of the link 4 is connected by the link 5 to a member 14 which connects to the rear flap 6. Movement of the link 5 causes the flap 6 to move linearly in a slot 10, and it is also connected by a link 12 to cause a rotating motion of the flap 6 so that it is located in its open position (FIG. 3) to extend downwardly.
U.S. Pat. No. 3,506,223 (Flemming) discloses an airplane having a lifting drive with two flaps which are moved from a closed position (FIG. 1) through an intermediate position (FIG. 2) into an open position (FIG. 3). The member 5 is attached pivotally to two arms 6 and 7 positioned and configured so that the flap 5 swings downwardly and rotates. The forward flap 4 is fixedly connected by the member 12 to a pivot location. The member 12 and the link 6 are interconnected by a link 13, and are driven by a linear actuator.
U.S. Pat. No. 3,585,757 (Ritchie et al.) discloses a passenger door for an aircraft which is adapted for use in high altitude flights where the cabin is pressurized. To open the door, the door is moved inwardly and upwardly and travels on tracks that have a non-constant curvature and extend upwardly.
U.S. Pat. No. 3,718,171 (Goodwin) shows a door for an aircraft, and more particularly for the cargo hold of the aircraft, where the door is made in two sections pivotally connected to one another. The door is hinge mounted at its upper end, and there are intermediate jacks 26 at the location of the hinge connection for the two door sections to provide limited movement of the two door sections relative to one another when the door moves to its open position.
U.S. Pat. No. 2,457,625 (Amiot) discloses a means for controlling the closing and opening of two lower doors P. The two doors are moved from the closed position (FIG. 1) to an intermediate position where the outer edges of the door are lifted upwardly by the arms 7 moving vertically, and then the arms 7 move circularly about center axis 11 to rotate the doors to the stowed position of FIG. 3 within the fuselage.
U.S. Pat. No. 2,731,221 relates to an aircraft door installation for high speed aircraft, particularly the type from which bombs or other loads are dropped in flight. There are right and left door sections, with each section comprising two door panels pivotally mounted to one another at 14. The outer door section is hinge mounted to the aircraft structure at its upper outer pivot location 13. An arm 15 extends upwardly to a pivot location, and the lower end is pivotally mounted to the inner door. As each door section is moved outwardly and upwardly, the two panels of each section rotate toward one another and in the fully open position the outer door is above the inner door, and both extend laterally outward from the aircraft.
U.S. Pat. No. 5,181,677 (Kaplin et al.) discloses a door assembly for an aircraft where there is a sliding door secured by tracks and is moved laterally between its open and closed position.
It is an object of the present invention to provide an improved landing gear door assemblies having a desirable balance of operating features, and which are particularly adapted to provide proper clearance for the landing gear, maintenance, and tire replacement and repair, while yet maintaining proper effective operation to meet the overall requirements of the aircraft.
The door assembly of the present invention is arranged to be used in conjunction with the landing gear of an airplane, where the landing gear has a stowed position in the airplane and an operating position. The airplane has a landing gear door opening through which the landing gear travels on a travel path moving between its stowed and operating positions.
There are first and second door assembly sections positioned in side by side relationship. Each door assembly section comprises a panel section which in turn comprises at least one panel which has a closed position extending at least partially across said door opening.
Each assembly section also has a positioning section operatively connected to the panel section to place the panel section in an open position by moving the panel outwardly and upwardly with a rotational component of travel to pass by one of said door opening edge structures to extend at least partially into said door opening and at least partially above said one of the door opening structures, and to be clear of the travel path of the landing gear.
In a preferred form, the positioning section of each door assembly rotates at least partially about a center rotation to provide said rotational component of travel.
Also in the preferred form the positioning section comprises a positioning linkage portion operatively engaging the door section to impart to at least one part of the panel section a radial component of travel superimposed over the rotational component of travel. The panel section has an outer end panel portion and an inner end panel portion. The outer panel end portion is positioned to move into the door opening and at least partially above said one of said door opening edge structures. The outer end portion in the closed position is at a vertical location lower than the center of rotation and in the open position is at an elevation above the center of rotation. The positioning linkage portion is arranged to move at least part of the outer panel portion radially inwardly relative to the center of rotation.
The positioning section is arranged so that a radially inward component of travel is imparted to the outside potion of the panel section at a location which is in an area at approximately at an elevation of the center of rotation about which the panel section moves.
In one embodiment, the panel section comprises an outer panel and an inner panel which are hinge connected to one another. The outer panel moves rotatably about the hinge connection relative to the inner panel at a location where a radially inward component of motion is imparted to the panel section.
Also in a preferred embodiment, the positioning section comprises a main arm which is mounted for rotation about the center of rotation, and the positioning linkage portion is mounted to the main arm so as to be generally rotatable therewith.
In a specific arrangement of the positioning linkage, there is a panel positioning link connected at one end to the outer end portion of the outer panel by a second end to the main arm in a manner to move through a path of travel and response to rotation of the main arm to move the panel positioning link in a generally radially inward direction and then with further rotation of the main arm to move the panel positioning link radially outward. This movement in a preferred form is accomplished by an extension link connected to the main arm and the panel positioning arm.
In a second embodiment of the present invention, the positioning section for each panel section is rotatably mounted about a center of rotation so that each entire positioning structure is arranged to move rotatably around the center of rotation. In the closed position, a center location of each panel section, which is approximately equally distant between outer and inner end portions of each panel section is located so as to be substantially vertically aligned with the center of rotation.
In the preferred configuration in this second embodiment, in the open position the two panel sections are substantially vertically aligned and located within the airplane structure.
The panel section in this second embodiment has a width dimension which is desirably at least as great as a distance from its center of rotation to an outside surface of the panel section. More desirably, the distance from the center of rotation to the outside surface is less than the width dimension of the panel section to minimize space requirements of the door assembly in the open position.
The distance from the center of rotation to an outside edge of the panel section is desirably no greater than one and a quarter times the width dimension of the panel section, and desirably no less than three quarters of the width of the panel section, and in a preferred configuration about the same as or one tenth less than the width of the panel section.
In the method of the present invention, the door assembly is provided as described above. It is operated in a manner so that the panels or panel sections of the door assembly are located in side by side relationship to close the door. Then the panel sections are moved to the open position by moving each panel section outwardly and upwardly with a rotational component of travel to pass by one of said door opening edge structures to extend at least partially into the door opening and at least partially above one of the door opening edge structures so as to be clear of the path of the travel of the landing gear. Other features of the present invention will become apparent from the following detailed description.